| 摘要 |
Holographic optical elements which operate at a multiplicity of wavelengths and which have reduced aberrations and a process for manufacturing the same are disclosed. The achromatic holographic elements are fabricated using substantially conventional apparatus employing a technique based on the phenomenon that any two playback wavelengths will be diffracted to the same angle if their construction angles are related to each other as the inverse of the ratio of their sines. In addition, in the case of holographic lenses, if the focal points during constructon are related to each other as the inverse of the ratio of the sines of their construction angles, the diffracted wavelengths will be brought to a common focal point. When used with a thick recording medium, the technique produces an optical element with a symmetrical pair of output beams having two independent focal points. |
